When I created SIGEV_THREAD timer, then start it by timer_settime. like this

the notify callback in the helper thread 'start' will be run when timer expiration.

But when I delete the timer, the notify callback will be run all the same.

This is not what i want. In actual use,  I encountered a problem.

I found that the 'timer_delete' function returns immediately after called.

The timer may not perform the delete action.

In addition, the SIGEV_SIGNAL timer can be deleted after called the function. 

So i think the function has different semantics for different types.

Is there a way to implement synchronously ?

Looking forward to your reply.